Thanks for the replies Mel and Dellwalker.
A bit of research showed the Sorbothane double Strike to be best for the condition but I've now ordered Xline as well to see which suits best. Yep, I know I should have rested but the Podiatrist said wear hard soled footwear like walking boots,, so orf i went. Only made things worse!!
Can't really understand it as less than two weeks ago I did a 7 mile walk over really rough ground without any problems.
Perhaps that triggered the problem.
Oh well, the body has reached it's seven score and ten design life. Now got wretched cataracts as well (thought the font on OS maps was getting smaller) It's all downhill from here I guess.