A mole on my lower back is red, and itchy. i have a picture and i'm not sure if i should be worried or not.

Yes, you should: In my opinion you should ALWAYS be worried when a mole acts up. Either it is being irritated, or it may be infected, or it may be becoming a melanoma. Some dermatologists say this is often the first symptom. It may not be serious at all, but no one can make this diagnosis from a photo. You are young and shouldn't take any chances with this horrible sneaky disease. You should be seen.