It is difficult to say whether the mesenteric lymphadenopathy is benign or clinically significant. For example the nodes may be enlarged because of TB or lymphoma. The only way to find out is to get ultrasound guided needle biopsy from the enlarged nodes.
I suggest you should get this test done since you have had persistent symptoms for 3 months. It is always better to get a specific diagnosis at an early stage when treatment is more effective.