Please help.

I skipped a period in March. Had one in April. I am now 5-6 days late for AF again. Before March I was usually only a day or so late for AF. I have been having cramps that switch sides almost daily. Gas and heart burn almkst daily and more. pregnancy tests are negative. Went to the doc the day AF showed on April 3rd. They did all kinds of tests with blood and he said everything he tested for was normal and pregnancy test was negative when he ran that so not a miscarriage. He did not examine me though, like nothing in my downstairs. Anyone have anything similar? What did it turn out to be or does anyone have any ideas on what it could be. I can't go to the doc till I get paid again at the beginning of next month.