Line of bumps on my leg not scaly not bug bite or itchy muscle under it cramps badly, cramping getting worse right below rash. dime sized bumps

There are few rashes: ...that are truly painful. One of them is Herpes Zoster (shingles). They tend to form linear clusters like you described, Because treatment is available that may hasten the recovery from shingles and prevent lingering pain, I advise you to see a doctor. Keep in mind that this is an educated guess, but a guess nonetheless. Hope this helps! Dr. Anne