Headache after morphine ?

[Comodo]

Hi, 4 days ago SWIM skin popped 10mgs of injectable morphine hydrochloride ampoule. The same evening (9 hours after the shot) he drank 2 double whiskeys (200ml) and went to sleep. The next day SWIM woke up with moderate headache with the course of the day the headache turned to light, BUT is still present 4 days after the shot (if it has anything in common?) its very light and not present all the time, but sometimes is quite noticeable. No other symptoms.
Is this common for morphine ? Anyone had a similar experience ? SWIM is new to opiates (this was his first injection)
p.s. sterile equipmet used, the shot went well, mild effect, mostly relaxation, some light strange taste in the mouth the first half hour or so.