Lilac tree buds dried out

bram1

We have a 12 foot lilac tree which we inherited 11 years ago. It has always bloomed and doesn't need any help. Last year one major branch dried but I put down to some major building work being done next to it (plus large cut in the branch). No other problems. This year everything has bloomed early in this very dry, sunny spring - except the lilac. It has a handful of tiny green leaves and undeveloped blooms but most of the buds have dried out and died. The buds appear brown outside and green inside which I understand might be evidence of a late frost but I don't think there has been one in London? The bark is vibrant green but the tree stem bark is quite striated (if that is the right word - not a gardener). In last two weeks have watered lightly every three days or so, avoiding over watering, as there has been no rain whatsoever for the last month. I've also gave it a very diluted addition of miracle grow about two weeks ago and some compost today. Some of the tiny leaves look as though there are curling up but also some evidence of healthy buds but they aren't growing. Any ideas? It#s a lovely tree but looking very sad