I started running for the first time this June, as I set a goal of 500 miles over the summer. I have played sports all my life, but I had never run more than a few miles during my first track season that spring. I realize that I completely threw away any chances of improving my 5k times, as all of my runs ranged from 6-22 miles, and only a few included speed work. I eventually ran a half marathon in 1:46:00 in late August, and then cross country was upon me. As of right now my 5k PR is 21:09, which I ran the day before I set a new half marathon PR of 1:34:00 two weeks ago. Ever since, I started feeling terrible, and I can hardly run without my muscles hurting. I also felt this way in late July, but the feeling went away. I went to my doctor, who ran some blood tests and said my ferritin levels were 5ng/ml, which is outside the healthy range of 30-200ng/ml. My hemoglobin levels were also really low, and my doctor told me to take 4 iron pills a day (1700% DV). Its been a week and I still am not feeling any better. I was wondering how long it might be until I can start training again. Another weird thing is that I went for a 3.5 mile run a few days ago, nothing hard by any means, and the next day my calves felt like they had been torn into a million pieces. Why would this happen when my run was nothing compared to what I have been doing before? When I do feel better, I was also wondering if it would be possible for me to improve my 5k time to a sub 20:00 by next June, which would mark my one year running anniversary. What type of workouts are most beneficial for a 5k? I certainly know that what I did this summer did not help me much except to PR in my half marathon by about 12 minutes. Sorry for typing up such a long description, I just wanted to provide you with as much information as possible.
Here's my Strava Profile if that helps:
https://www.strava.com/athletes/41881572
(Hopefully the link works)
Thanks for the help!