Why does my map turtle keep twitching?

i left my turtle outside to get some sun cuz it was a realy realy hot day and he must of climed out of the water and got out i was in the house for an hour and completly forgot went outside and he was gone , after an hour of looking everywhere he was quite away down the back of my house in the lane tryin to climbe up the railin in loads of stingy netles but with the sun shining hot on him

im so scarred cuz he seemed okay at first but then 15 mins later i noticed his whole body just twitchin out as if he was fitting and he didnt know wat to do with his self just going mad swimmimg round and every part of him was twitchin i left him for a few hours and now his head just like spazams out just twitchis and its like if hes blind cuz when i put food in he was going for the food but was completly off target and kept missing im so scared cuz hes my favirote turtle i have three and i love him so much please help me i need advise and i need to know whats wronge with him