My back is killing me tonight! Usually it's stress or picking up DC related and just 1 ibuprofen is usually plenty to help me ease off to sleep and rest enough to feel better by dawn.
...However, just found out DP has used them all for his hangover a couple of days back! 
BUT, just found DC's Neurofen for children bottle during the cupboard raid.
Says 1x 5ml spoon = 100mg so 2 spoonfuls should do the trick.
Just sense checking there isn't some obvious red flag I'm missing in my eagerness to get to sleep!
Thank you