Stomach ache. Area or some other cause?

For the first 4 days I was having a gas problem and my stomach ache I was feeling so uncomfortable all day as the pain was all day but the intensity was light and feeling pressure in my lower abdomen also and my stomach was rumbling also and tightness in my lower abdomen area . Then I consulted my doctor and he gave me medicine and antacid for 2 days. today I was not having pain and suddenly pain started again and little gas problem but feeling like I have to be fresh and having light lower back pain near my hips and I am not feeling nausea taking my meal at proper time . Last year i had medical abortion but few pieces was left so I opt for surgical method. This year I had unprotected sex for which i had ipill but my all test were negative. I am so stressed are these problems related to my uterus or problem in my pelvis area or some other cause ??? Should I go for pelvis ultrasound or normal lower abdomen ultrasound I am confused and stressed too please help me out thanks in advance 🙏