35 weeks pregnant and swollen feet for 3 days even though iv rested?

since friday iv had swollen feet well 1 foot last night it was really painfull, i woke up early hours this mornin with a banging headache and nowthis mornin with in 1 hour my foot is swollen again but if i touch the top of my foot it leaves an imprint, is this ok or am i just panicing about nothing iv never had it in my other pregnancys but do suffer from blood clots