I've Noticed Over The Past Several Months That My Legs

I've noticed over the past several months that my legs swell. I try to watch the amount of liquid intake, but sometimes I feel like I haven't really drank enough to warrant the amount of swelling mainly from my knees down, but occasionally I feel it all over. At work I do the best I can to keep my legs propped up. I have thyroid disease........completely dependent on Synthroid and I also take Cholestepol for my high cholesterol.