This sounds all to familiar to me as well! I suffer from frequent migraines, anything from hormonal changes (thats my normal trigger and indication of TOTM), any sort of stress, change in weather, pressure.. etc...
Have you had a migraine attack in the last few days? Could it be a side effect of the tablets that you have been taken for your knees?
If you can, try drinking cranberry juice or grapefruit juice. If you arent too of-fay with either, try putting a little in your glass and filling the rest of it up with water.. the antidioxants in the cranberry and grapefruit juice are meant to decrease the pressure about the blood vessels and allow them to flow more easily (my acupuncturist swears by it and whenever I get an attack thats what I only drink and it seems to help me)
Also try take motilium or something like it to soothe your stomach. I take paramol which is a combination of paracetamol and motilium.. again sometimes it works, sometimes its just like taking sweets!
I hope you feel better soon.. PM if you need a chat xxxx