brakes acting weird

[400 dollar yaris]

When I first start my car and go to press on the brakes for the first time my car acts sort of weird like almost like the brakes get stuck or something. At first, I thought it was just because they could be wet as its raining a lot where I'm at, but now I am a bit more skeptical. I think the rear drum brakes may need to be replaced, but I haven't had time to look yet this morning, does this sound like something that may be true or am I maybe looking at a bigger issue
? It's as if the back end raises up a little bit when I'm first backing out of the parking space in the morning and it has been doing it for a few days now. Is it possible for water to get trapped inside the drums?