i had something vaquely similiar,about 2 years ago,it was suggested that i have ammnorreah its a lack of periods due to stress and
unstable hormone levels,i also got like a mini cramp and mood swings, i used to go about 3months without a period.. yes i stressed more than once,a blood pregnancy test also came back negative,my suggestion is that you have a check up with your gyni or do some research the subject,i was put on the pill which has solved the problem.