All the comments here have been so encouraging to read so thank you all for taking the time to read my message and offer some reassurance.
The fact that many of you have already achieved what I am aiming for is awesome and makes me see it really is possible .
As part of the 5k programme, today I ran for 3 minutes (I did this twice) and I didn't struggle with it. I was so elated when I finished. I'm a long way of my goals but I must remember that less than a month ago the three minutes I did today seemed impossible.
I am not a runner by any means but I have always wanted to be and so I have taken the plunge and I'm doing a Couch25K plan. I am currently at the beginning of week three of nine and can run for about 90 seconds without wanting to pass out (which is an improvement on last week where I wanted to pass out at one minute). As a motivator, I have signed up for a 5k race on May 18th and would like to finish in less than 40 minutes, but there is no time limit for this. The thing is, I signed up to run a half-marathon and yesterday my entry was accepted. It's not until late November but I have to complete the first half of the race in 90 minutes or less or I get directed to retire and will not be allowed to finish the race. Is it possible for me to be trained enough to run a half-marathon by November 2013? Considering I can only run for about 90 seconds at this moment in time!?
I am also doing the Couch25K NHS plan, I'm currently on week 3 and I am having the same exact problem and it feels much worse in my left ankle. I would describe the pain as a sort of growing pain sensation.
I think icing it as mentioned above is a really good idea!