Im having pretty much the same problem, ive been thinking what i had was fungas gnats but it turns out i have aphids, i know this becauae the fungas gnat larvae have black heads on them and what i have are crawling around so they cant b larvae. Also when i water my plant the same thing happends they all start freaking out and crawling to the top of the soil then dig back down. I just checked the aphids forum out and it was very help full to me and im gonna get some neem oil pyrethrum n botanigard. Some good shit. Best of luck to ya