Health problems, could anyone help at all?

Hey guys, so over the past month or so I'm been experiencing a lot of problems with going to the toilet! I was constipated for about 4 weeks or something, and I was extremely bloated.. Still am abit bloated, I also can't breath 100% not sure if that's front the bloating, And now I'm having problems with my menstrual cycle, my period normally lasts 5 days.. For the last 3 periods I've had they have only lasted 2 days or less.. I'm not pregnant either, Doctors can't seem to give me a straight forward answer and was wondering if anyone on here has experienced this before! I'd also like to add that I have really bad anxiety, thought that would be what is causing me all these problems! I'm started to get really worried, so if anyone could help that would mean a lot!