Upset Stomach 20 weeks + 5 days.

Brandy
This is my fifth pregnancy (4th time to make it this far). This is the first time I can remember this happening during pregnancy. I woke up this morning with diarrhea out of the blue, and my stomach has been a wreck all day! I suffer from chronic constipation so this is baffling me even more because of that fact. I haven't eaten anything different than I normally do. In fact, I haven't had that much of an appetite this past couple weeks. Any time I have eaten anything or even drank water today I have to go #2 within 30 minutes. Anyone else experience/experiencing this around this time?