I also suffer abdominal pain related to NSAIDs.When I was on a combination of Toradol and Naproxen it was brutal and I ended up in hosp. on I.V. pain meds a couple times.Now I take Pariet daily and that has helped a great deal with the abdominal pain, esophageal reflux and indigestion.I also make sure I eat something before taking meds ie.a couple of biscuits or soda crackers. Meds like Zantac are available over the counter, but you should speak to your physician about the pain you are having and he/she may prescribe Pantaloc, Pariet, Zantac, Cytotec, etc. used to treat the symptoms.
As far as the constipation goes, again related to pain meds, you can try an over the counter stool softener like Colace or take Prodium or Metamucil daily or as directed by your physician or pharmacist. I can't tolerate the Colace as I get vague lower abdominal pain/cramping and nausea. I take a combination of Calcium Citrate with Vit. D and Magnesium Citrate which not only helps with constipation but has decreased muscle cramps to my calves, shins and feet. Again, you should discuss the issue with your pharmacist/physician. You can also increase both your water intake and dietary fibre as well.