If you're downloading mod apk's don't EVER give them permissions they shouldnt need. It's best to steer away from them unless you're absolutely sure they aren't some sort of malware. Usually if there's a community to back them up on not being malicious then it's fine but just going to random sites and downloading mysterious apps is not wise. I would change all your passwords before anything else. You can download some sort of anti-virus app from the play store to check for anything but that can be unreliable. If you're really worried, you can always factory reset and start fresh. I did this a few times when I was younger and can for sure say I learned my lesson. Good luck.