I've Been Having Dizzy Spells For Several Weeks. Literally Each

I've been having dizzy spells for several weeks. Literally each and every time I stand up I get so dizzy I have to grab on to something so I don't fall. I've tried getting up slowly but it doesn't make a difference. Sometimes when I have a dizzy spell my hand will have spasms for a few seconds as well. It's really strange. I have rheumatoid arthritis and hypothyroidism. I don't believe this is due to any of my medications because I've been on the same meds for years. Thank you.