Feel like my intestines andstomach to bulge. No pain no fever but, feel like vomitting time by time and caused weakness. I suffer from constipation..

Nausea stomach bloat. Constipation can cause bloating/ nausea. . How often do you go? For constipation drink -3 liters water/ gatorade / day, prune juice once a day eat greens 1 bag (12-16 oz)s day, fiber foods - sweet potatoes, avocados . Also consider food intolerances, irritable bowel , rarely mass or nerve issue like megacolon ( usually gastritis gallbladder inflammation cause pain , diarrhea) f/u/ w/ GI.
GI symptoms. such as you mention need to be evaluated by your doctor or a gastroenterologist. Please see a doc. You MAY have a digestive issue that can be cleared up easily by probiotics or something more complicated. Peace and good health.