I've always suffered, but the last few years, as I approached and entered my 40s it's just got worse and worse. TBH I was a pretty horrible person and miserable for 10-14 days out of every month.
The only advise my GP could give me was that "in view of your age it won't last much longer" 
Anyway, I did loads of reading on the subject and although there were differing views, the common themes were moderate exercise (which I have always done) reduce salt, sugar, white flour and animal fats and increase iron, potassium, magnesium and calcium.
As this all seemed sensible advise anyway, over the last 12 months I have started to take a multi-vit, swapped my toast and butter snacking habit for a handful of cashews or almonds, porridge with sunflower seeds for breakfast, lots of veg and moderate fruit everyday, cut out ALL refined sugar. I never have a pudding/biscuit/cake now and no processed food (sugar & salt). TBH after about 10 days you stop wanting it anyway, although very hard to start with.
I saw some improvement as soon as I'd conquered the sugar, but the last few months have been amazing. I managed to organise/pack for a holiday in July (which was always a trigger) without even a mild disagreement with DH and this month my period has arrived without me even realising it was due (cycle has always ranged from 24-31 days)
I felt myself "going" yesterday when DS1 was arguing with me about time to turn off PC, but I reined it back in and dealt with it calmly and there were a couple of days when poor DH was a bit irritating, but I didn't come close to starting a row. Work has been very stressful indeed this week, but I never felt stressed, iyswim.
Bloody GP told me there was nothing I could do with diet!