I have a flowering currant bush which was a cutting from my mother in
law's plant. I've had it about 5 years or so and it is around 4 ft
tall now, and was growing well. Late last summer I noticed the leaves
on a small branch looked a bit shrivelled but the rest of the bush was
fine, or seemed so.

This spring it hasn't done anything at all. It has what looks like
buds all over but they are brown, not green. No sign of any flowers.
The stems are not totally dry and brown inside. It still seems to have
a bit of sap.

I did wonder if my neighbour had used a weedkiller which might have
got into my soil under the fence, but other plants nearby look OK, so
I don't "think" it's that (I can't ask them because they will get all
snotty and paranoid if I do)

Anyone any ideas as to whay might kill a healthy flowering currant
bush? Is it worth leaving it in the ground in case it rallies round?

I live in Hampshire, and my soil is clay.

Thanks.