Don't listen to the previous comment. It's not weird. Everyone, whether they're willing to admit or not has some sort of a fetish, and some have more then one. It's normal. Maybe the reason why you now feel turned on by someone else tickling you is because before you've always wanted to do that to someone else. It's a complicated subject but sometimes feeling work in reverse and you suddenly feel the opposite feelings, like for example on another person instead of yourself. I hope this helped.
That's so gross and weird I've never understood foot fetish LOL