The OP doesn't have herpes. I get mouth ulcers often, though they tend to come and go in phases. Here's what works for me to keep things under control:
- Try using toothpaste that doesn't contain SLS (sodium laureth / lauryl sulphate), that seemed to make the largest difference for me. It's fine when used on the skin as it is with many shampoos and shower gels but I reckon it tends to be too strong when used in the mouth.
- Don't use a mouthwash that contains alcohol as that can irritate things further. Try something like Dentyl that's alcohol-free and adheres to bacteria in order to pull them from the mouth.
- De-stress. For me, nothing causes ulcers more than being stressed out.