I had my sleeve on 7/11/18. I can't be sure, of course, but you might be having esophageal spasms. Prior to surgery, in addition to Oxycodone 5mg, my doctor also prescribed prn sublingual Hyoscyamine (Levsin) for post-op discomfort which feels like cramping. It works and provides relief. For sleeping for 4-5 hours I take the oxycodone only when needed. I also noticed when I don't take small sips, I get some mild cramping. Check with your doctor. Levsin might help.