Started exercising 2 wks ago started feeling pain in the top of my butt crack feels like a lump & its sore hurts to sit directly on my butt what is it?

Need to examine: It is not feasible to provide a meaningful opinion without physical examination, however what you described suggests a friction blister/sore. Do not give up exercise, but do a different one. You may walk or jog, or use treadmill. If you are overweight, you may resume the exercise you were doing after you lose weight and the sore heals. I commend you for exercising. For good health -Have a diet rich in fresh vegetables, fruits, whole grains, low fat milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex. Get HPV vaccine.