Usually My Period Only Last 3 Days But This Time

Usually my period only last 3 days but this time it started on the 11 and didn't end until the 16. Then on the 29th I started spotting a light pink and that lasted until the 3rd. I have had stomach pains and every time I eat I get sick to my stomach and I have to eat a lot and I have a lot of gas. I don't know what to do.