What Causes Severe Constipation While On Ibrufen?

this is embarrassing. I am a 52 year old, chronically obese man (400lbs) and Im on ibuprophen for joint pain. It has caused me to be so constipated, my fecal matter is bunched up like a rock and I can't go.
I dug out some and used vasoline to try and lube the area around my anus, but that has not worked yet.
what can I do?