Feeling of something big in rectum that can come out abit,even with straining,keep having urge to poop.still able to pass gas.how to ease the problem?

Some options...: Colonics &purges are popular but should be avoided & can not be recommended (see earlier healthtap answers). Use of irritant laxatives are safe for the short-term only. Fiber supplements, stool softeners, &lavage agents like MiraLAX (polyethylene glycol) are safe. Rx drugs are available based on work-up of your cause of constipation--rule out pelvic floor dysfunction, dysmotility/dyssynergia, etc.