It seems like there are two different concerns here.
One is your pain in the lower stomach area and the other is the numbness
and burning sensation in the left foot, difficulty in walking.
To conclude on the cause of your stomach pain, an ultrasound
scan will be definitely helpful. You may consider getting it done.
The symptoms on your feet suggest a Peripheral neuritis
kind of picture. It can be due to Vit B12 deficiency as well. One important thing to rule out here is Diabetes
. Please get your random blood sugar tested as well.
I wish you quick recovery and a healthy life.