Protein shakes are good shit man. Try to not get down about this, when you have addictions to other substances, and I am assuming you generally prefer coke, its easy to just give whatever else is around a go.
Been there, done that. Hoovered my way through a mountain of coke off and on, and comparing the two drug comedowns, meth is Goliath and coke is David. So no wonder you are suffering. Meth is highly highly addictive as within a day, you'll be remembering the buzz and forgetting the comedown. Its how it hooks you in man. So just remember, it sucks ass and dont go near it!