Guinea pig...plz HLP!!!!PLZ!!!?

i gave my piggy lettuce and i just found out there not suppose 2 hav that wat do i do?!?!?!it says that they get sum diease frum it and my piggy ate a medium sized leaf of lettuce.i cnt take him 2 the vet.so since i cnt do that wat can i do since im stuck at my house with him!?!?!?plz hlp i dnt wnt himk 2 get that disease