When trying to accelerate RPM's shot up high and vehicle would not Move

There were a few things that happened but they happened months apart and never had any signs before any of them. For instance we were driving 75 down the highway then all of a sudden felt this really hard kick and then the rpm's shot up. Then it just start slowing down and I couldn't get it to do anything. My husband got out looked under the hood and everything didn't see anything. So we just randomly though lets put it in four wheel drive see if that will help. So we tried it and it worked. When we got it home my husband cleaned out the transmission pan and it ran fine for like six months. Then all of a sudden my uncle had borrowed it and he couldn't get it to go in reverse that happened to us one time also, but then we push it in reverse usually then just continued driving and try reverse again and it would work fine. However, the last time my husband and I were sitting at a stop light and we were speeding up then the rpm's just shot up and it like revved up real high and we couldn't go in reverse or anything and still haven't been able to move it. Mind you this all happened months apart so my question is, did my transmission go out or could it be something else?