Cat's hind leg keeps twitching! Is this an emergency?

His hind legs often twitch after he walks away after standing over his meal and eating ( I assume it's like pins-and-needles), but they usually always resolve within a second or two.

For the last hour or two, his right hind leg keeps twitching- and he'll immediately stop to clean that paw- quite vigorously and almost violently, as though something's really bothering him. His right hind leg's paw pads are almost red from all that cleaning. Is a twitching right leg benign or can it be a sign of something more serious?

It's after hours over here and any after-hours/emergency care is really, really expensive. If it's likely to be an emergency I'll take him right away, but I need more information on what this could be because I've very limited funds right now. But at the same time I don't want to be left saying 'I wish I'd done more'.

The main thing you need to determine is if the problem is neurological, in which case it can wait until morning, or if it's circulatory, i.e. might he have a clot in an artery that could occlude circulation to his legs.  I'm not a vet and don't know very much but I DO know that if his feet are cold, or significantly cooler than his front feet, that could indicate a circulatory problem and thus an emergency.

Just wanted to say thanks (and sorry for the late reply)- it seems a claw was bothering him. Thanks for the advice about the temperature of his front and back paws- after feeling his paws I was more assured that it wasn't a blood clot or circulatory problem.