This is a VERY common problem for cyclists - you find 30 mins of gentle exercise soooooo easy; and then you damage some bit that you never use on the bike! (generally lower leg somewhere)
(most people luckily just get VERY sore calves, which gradually goes away with each run. )
Yes, sounds familiar. A few times I've tried to start running, gone too far and too fast from the outset, and ended up in pain so given up (top tip: don't randomly decide to see if you can run 10k in one go having not done any running for about a year. Stairs might be interesting the following day.
)
At the moment I'm going for the gentle approach: I'm using a treadmill (simply because it fits in around other gym stuff I do - time before/after classes) and making myself build up gradually. I now know I can do 5k comfortably and not feel any pain the next day, which is better than I've managed in the past (my usual thing currently is 5k on a Monday morning - I figure that if I can manage a tough spin class on Tuesday evening, I'm fine). I also do 15-20 mins of "intervals" (slow and slower!
) once a week. Next step is to take it outdoors and go for a bit longer - but I'll be going very slowly to begin with while I try and build up some distance. I find that if I just take it easier and slower than I feel I "should" be, it's ok.
I'm also fairly sure I'm built wrong for running - my knees cave inwards, which the internet suggests is due to weak glutes, so I've bought some resistance bands and am going to work on that.