friends not feeling like friends anymore

i have a couple friends that i've known for years but lately i've noticed that when i hang out with them i honestly don't feel the best. i hung out with one of them recently with a couple of our mutual friends and they were talking to me kind of in a condescending way and sort of questioning some of the things i would say. i will admit i am a bit of a jokester but this person has known me long enough to know when i'm being serious about something. when one of our mutual friends asks a question and i genuinely answer it, my friend looks at me as if i'm a little kid and i don't know what i'm talking about. i usually would just say whatever and move on but this has happened a couple of times, but never when it's just the two of us hanging out. when we're alone this person even asks me for advice on things going on in their life but when other people come around, i'm treated like an airhead. i'm not the confrontational kind so it's really hard for me to talk to them about this. what should i do?