Replying to DR NS, Diagnose Me

So lately, off and on, I'll get pains in stomach, but just on the left side. It's always on the left side, right under the ribs. It's not a normal pain, but rather a pain that feels like there is some sort of acidic material inside me and its like eating away (like a gurgling feeling sort of). It has been going on for a few days now, and i'll wake up during the middle of the night with it rumbling, so its causing me less sleep.

What is wrong?