Swollen paw between toe

Hi, my dogs paw in between the toe is constantly swelling so badly then it will go down again then swell again. Does any one have an idea what this it? It was squeezed about a month ago and a small bit of grass seed popped out and we thought that was the problem bur could there still be some in there? thank you 

Hello - more grass-seed 'bits' (additional foreign material) in there might explain this; what you are seeing could be an immune response that may push more foreign material to the surface.  However, pain relief and protection of the skin can be vitally important in the meantime and it may be that your vet wants to rule out one or two other possibilities at some stage (for example, tumours) so you'd be as well to let them assess it again.