All your symptoms seem to be allergic reactions localised to your oral cavity. But since it is occurring in recent times there could be other reasons behind it. Only when we can see the blister or swelling as mentioned by you or the ulcer in your palate we can decide on the type of your problem, diagnose and proceed with the necessary treatment.
Next Steps
Next time just don't wait for it to heal by itself and visit your dental surgeon immediately. Clinical examination of your problem is necessary before providing you suggestions online.
Health Tips
Avoid home remedies and do find time to visit your doctor. If you have severe time constraint try to avoid outside foods as well as spicy foods at home and this will give you an idea about the frequency of occurrence of the problem along with severity helping you in future to explain during dental checkup.