Alcohol & Drugs: MIP, MIC, Intoxication MIC while on probation for MIP (Urgent)

[BMcMath5]

For starters, i am an almost 20 year old college student in Texas. My school's town has a student run "carpool" service that students can call if they need a ride anywhere (whether they are drunk or not). Two of my friends and i were walking, not showing any signs of being remotely drunk, to a nearby McDonald's to meet up with the carpool service to get a ride home. On our walk, a cop pulled up to us and told us to sit on the curb. They had busted a party nearby and assumed that we had been at it. We told them that we were just walking to meet up with carpool when they started questioning us. I had drank 2 beers at the party we had been to earlier, but it had been several hours since i drank. They started yelling at my friend when he asked them a question pertaining to a lawyer, and pressured us into admitting that we had been drinking. He gave me and my friend MICs and let us continue walking to meet up with carpool. The problem is that i had been given an MIP (another sham within itself) in the fall, and was in the process of serving my community service and probation. (I was done with 4 of the 6 months of probation) What can i expect to be facing? If i get a lawyer, what are some possible outcomes? And, are they allowed to just roll up to us and more or less interrogate us for no apparent reason? -Thanks for any feedback. Sooner the better.