What precisely does it mean to "feel crap"? Is that how you would describe it to a doctor? You seem to also be making broad generalizations. Overall your comment is providing zero insight whatsoever wrt creatine.

In my experience, those with creatine intolerance, especially if assuming it's not taken late in the day, have unresolved excitotoxicty/inflammation/pressure/headache/migraine issues in their brain.

Also, be mindful with blends as they can be fairly dangerous. It's best to get an isolated creatine monohydrate product that is not a blend.

Check your blood pressure. It is very possible that there is something else in your blend that is raising your BP.