Hello, My Name Is Vivek And I Have A Throbbing

Hello, my name is Vivek and I have a throbbing pain in my anus especially when the anal muscles contract. This pain is there since a week now and has increased. Earlier the pain was not there when i sat for long hours, but now when i sit for long hours and then get up, it hurts. It all started when i had non-veg food at a road side vendor. Whenever I go to the loo, all the stool doesn't come out and I cannot apply more pressure as it is painful.
Please provide me some help.