"You cannot swim after eating."
Translation:No puedes nadar después de comer.
después de go together (it's just one of those constructions we need to think about as a pair) and then is followed by the infinitive in Spanish.
It's English that's fickle about sometimes we follow with an infinitive ("to ...") and sometimes with a gerund ("-ing"). You shouldn't change the Spanish construction based on the English one.
It looks right to me. Click the button below the question and say so. I've been sticking to verb forms that have already been introduced, but I'm unsure why that would be necessary. When I searched for your answer on Google, I found none just like it, but 65 with ...despues de comer. That sure doesn't mean yours is wrong.