In reply to Gone for good:
Q: Are you injured?
A: No: Q: Is there a directly equivalent model of you shoe that you can buy?
A: Yes. BUY IT. IN fact, BUY two pairs now.
A: No. Swear. Then go to a running shop and try a whole load of pairs on. Buy the ones that are closest to feel of the old one. Hope you don't get injured.
A: Yes: Q: Is is related to your shoes, even remotely?
A: No: See a physio. Then get new shoes as above
A: Yes: See a physio. Then get advice as to the type of shoes and or orthotics which might help. Do all the exercises they suggest, Buy new shoes on their advice AT A RUNNING SHOP where you can try them all on. Get the ones closest to the advice you were given. Hope they don't make the injury worse in some other way.