If you are running more often and more miles than previously then it is going to take a few weeks to get used to. Also, it is very important that you keep your easy running slow enough, I'd say at least 8minute / mile.
It's up to you on the speedwork, I can't say that you definitely won't lose some of the benefits of the previous months, but it will possibly make you more likely to pick up niggles if you keep it in and increase the number of runs/miles.
Also do plenty of stretching after EVERY run.