Please bear in mind that this is not a diagnosis, and I am not trying to be alarmist, but I strongly suggest that it would be a good idea to see an ophthalmic specialist as soon as you can, especially if the condition is recent.  Rainbow vision in one form or another may be a symptom of vision-threatening conditions such as glaucoma and detached retina.

By the time that such conditions have developed to the point that you are forced to see a doctor, a lot of the damage has already been done.

Some people have confused such symptoms with migraine, stress and the like, but if anyone suggests that it is anything of the kind without professional inspection of your intra-ocular status, he is gambling with your vision. It takes a large number of unnecessay inspections to trump loss of vision even in a single eye. (Well, that is only one opinion of course,  but...)

If it were my eyes,  I would be camping out on the specialist's door, and I don't mean a dispensing optometrist. (No offence to optometrists, but I think that any practising member of the fraternity will agree that this sounds like a job for urgent medical inspection, and not just for intra-ocular pressure!)

Good luck!

Jon