85 SI Transmission Problems

:banghead: So my boyfriend has an 85 prelude si that he got from his grandmother. Lately it has been running funny, the entire car shutters while we are driving, idle keeps jumping around but as of a week ago the tranny started acting up. It would shift really hard but now, it wont shift out of first and the rpm's go up but the car doesn't go any faster. Best way to describe it is the rpm's go up but you can't feel any struggle for the car to go any faster. Hard to explain. I'm thinking that either the tranny is toast or it just needs a new filter and new fluid. I added some fluid yesterday and noticed the old fluid was brownish and has flecks of dirt or something in it. Please help am absolutely desperate on this. HELP!!!:frown: