Blinking back tears of happiness, champion swimmer Neil Gilson looked over at his children as they reached the bank of stunning Lake Geneva. He told The Mirror: “I can’t believe it - I’m incredibly proud.”For the last 200 metres of his swim across the 72km long lake, he was joined by Chloe, 12, and Jack, 10 - the son who inspired his world record setting challenge to swim all 10 of Switzerland’s largest lakes.Completing the last leg in 23 hours and 15 minutes, he didn’t quite break his 2024 time of 22 hours (which set a world record). But he set new world records with all his other lake swims.When the 40-year-old, who runs the Sandy Cove hotel in Berrynarbor, North Devon, with his wife Lucie, emerged from his last swim on Wednesday, Guinness World Records recognised him as the first person to swim all 10 lakes.‌Neil said: “I had tears in my eyes, my goggles were steaming up. To see both my children swimming alongside me was pure joy. But for Jack, it’s something we never thought would be possible. It was a dream come true. I’m over the moon.”Also dad to Ruby, four, Neil’s lakes challenge has raised more than £7,000, so far, for PANS PANDAS, a small charity that took care of his son after he developed a rare and terrifying condition.Jack was 18 months old when his behaviour changed dramatically and alarmingly overnight. Neil says: “Jack developed severe anxiety and became really nervous about everything. He had a bad tic, where he would rub his ear on his shoulder, which became constant. He barely ate anything and had extreme tantrums. It was traumatic for us as parents - we were frantic with worry.”‌Doctors initially thought Jack had autism, then later Tourette syndrome. Neil and Lucie were desperate for answers, but none came. Then, when Jack was three, Lucie chanced upon a viral social media video that changed everything - showing a family on ITV’s This Morning, talking to a doctor about their son.Neil says: "The headline was something like ‘mould turned my son evil’. Now, I obviously don’t like the word evil, but at the time - we could relate.’Spotting the similarities with Jack’s altered behaviour, the couple tracked down Dr Tim Ubhi, who was from the London PANS Clinic, and made Jack an appointment.‌Blood tests confirmed he had the streptococcus bacteria - which causes conditions like scarlet fever and strep throat - in his system. Neil says: “He was having a misdirected immune response to the illness, which his body was unable to clear.”Jack was diagnosed with PANDAS (paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections) - debilitating conditions in children that trigger sudden, severe neuropsychiatric symptoms, like OCD or tics.The condition causes the body's immune system to mistakenly attack the brain and the resulting inflammation triggers abrupt behavioural and neurological changes.‌Given a longer course of antibiotics to wipe out any infection, Jack then had his tonsils removed. Neil says: “We started to get our little boy back. It was incredibly emotional. We haven’t looked back.”Infections like winter bugs still cause flare-ups, but Jack now understands what’s happening, so can tell his parents, and they then take appropriate action.Keen to raise money for PANS PANDAS UK, the charity which supports the 7,100 UK families dealing with the conditions, Neil, who in 2002 British Championships came second in Britain in the 1,500m freestyle, dived straight in.‌He says: “I felt powerless, so did what I could - swim. I did my first challenge, a 24 hour swim for PANS/PANDAS UK in a Scottish lake, in June 2020. Then I did the Bristol Channel in July 2021, then Lake Geneva in July 2023 (first attempt) and 2024 (second successful attempt).“There are people desperately searching for answers, just like we were. My mission is to try and get the information in front of their noses.”Swimming 382 km in all, during the 10 lake challenge, Neil battled extreme fatigue, strong currents and freezing temperatures from the run-off from the Alps.As well as Geneva, last year, he swam Lugano (30.7km), Constance (65km), Biel (15.7km) and Neuchantel (37.4km) - achieving new world records for all of them.‌This year came Maggiore (59km) Zurich (37km) and Zug (13.8km), Lucerne (36.2km) and Thun (16.6km), setting five more world records, before finally ending on Lake Geneva - the biggest of them all.Neil set off at 2pm on Tuesday and stepped back onto the shore once more at 11.15am on Wednesday. He says: “It was a tough, really tough swim, though. I got unlucky with the currents. And then it was a long night. I started falling asleep while I was swimming. Then I got really cold because I was so tired.“I wanted to quit, to throw the towel in, so many times. But I pictured my family at the end, and their faces. And somehow I kept going. I did it for them - I did it for Jack.”‌Jack adds: “I felt proud to help Daddy finish his challenge and hope it helps lots of other children - I also felt a bit nervous being in the lake. I’m happy that Daddy has finished and hope he has helped other children have a better life.”*For more information and to donate, see panspandasuk.org; donate HERE; and for more information about Neil, see neilgilson.com