Yes indeed - a lot anxiety (and you have reason to have a lot if you're afraid you have had a sexual encounter with someone you think may have passed HIV to you) can cause many symptoms
pain though? I don't think so. I've never seen any patient who exhibited foot pain because they were afraid they had HIV. I've seen diarrhea, vomiting, insomnia, aches and pains, headaches, nightmares, but never localized foot pain. (localized meaning in the same spot for months.