Both suddenly developing soft spots?

Sorry I didn't really know how to describe it.. but you know when you get 'the spot' when you're scratching them and it makes their back leg quiver?

Well we've had them for years now and I'm forever scratching them all over and in new places, and they've never ever done it before. But now they've BOTH got a 'soft spot', they developed them at the same time.. Its definately a new thing, they've never had them before. Could it be health related?

I don't think they're being excessively itchy, I've not noticed them itching more anyway so I'm not sure it's a skin problem.. just wondered if anyone has any ideas?

Don`t take this the wrong way but is their flea treatment up to date?

Thanks for your reply! You're right on the money, they have fleas

We put Frontline on them on Saturday and haven't spotted any since so hopefully thats the end of it, will be hoovering every day till I'm sure!