My 5yo son as been overly affectionate and it makes me uncomfortable, I dont know what to do.

This is going to be a long one lol.Hopefully this doesnt come out wrong, my son has always been a cuddle bug since he was a baby and I love it but it's kinda gotten out of hand and I cant get him to understand what hes doing is...... not necessarily bad but overbearing.For context, theres been multiple issues where hes been inappropriate with other kids. There was an instance where he was shoving his hands down other children's pants at school. His teacher assured me its normal for kids at that age but she just wanted to let me know. (Hes my only child). This hasnt been an issue since, as I know of.We caught him and my niece under a blanket with her pants down and his face infront of her butt. My neice stated he kissed her butt hole. My sister and I were mortified, they are never alone now.Now for me, he CONSTANTLY wants to kiss me. Always on the mouth. Trying to redirect the kiss just upsets him. It's not just a sometimes thing it's literally all the time all day, everyday thing.Hes humped me numerous times and constantly grabs on my body/butt. I've tried sitting down and talking to him to try to get him to understand he cant do things like that but nothing works. I'm at a loss and it makes me sad that get uncomfortable being around my own child because hes grabby.Please, any advice would be greatful! via /r/Parenting http://bit.ly/2DKqxMG