If you're getting bubbles/air then it has coliform bacteria. Toss it. I'm sorry!
Good raw milk should coagulate into a smooth uniform curd with just a bit of whey on top by 24 hours. Should smell like delicious tangy buttermilk.
I wouldn't worry too much about temp - I warm to 100 initially and then leave at room temperature (70). Don't worry about contamination from the room - the milk already has plenty of bacteria from the cows' biome, teats, etc.
Try again with the same milk (just one generation) - but if it takes more than 36 hours or has bubbles or smells like anything other than nice buttermilk, the milk is not clean enough. You'll want a new source of raw milk. I disagree with those saying you can make a good culture after many generations of clabbering. If the milk doesn't clabber properly the first time, it has coliforms or other undesirable bacteria and is not something I would want in my kitchen. Yes, it is beneficial to refine a good culture through successive generations, but if the milk isn't high quality to start with then it's not wise to use it in a raw state.
Unfortunately coliforms are common in raw milk (not usually an issue in regularly tested Grade A raw milk for retail (raw) sale though). You may need to try various sources to find one that's suitable. Incidentally, the clabber test (how well milk clabbers in 24 hours) serves as a fairly accurate representation of raw milk quality and serves as a handy quality test when lab reports are not available/feasible.