Preeclampsia???

Ha
So I've heard preeclampsia can be more commonly found in younger pregnancies. I'm 21 yrs and 36w 5d. A couple of days ago I was noticing my huge leggings (I specifically got for pregnancy) getting super tight around my ankles. I took off my sandals and my feet were so swollen (I haven't dealt with swollen feet at all up until now) there were indentions from where the straps had been. I've had this ache in the back of my head/neck for a couple of days as well. & my biggest complaint in the past week has been severe pain in my upper right belly area. All of these symptoms are indicators of preeclampsia and I'm starting to get worried. Has anyone experienced it before?