Can "My head hurts a lot right now, it must be a cold" be accepted?
Makes perfect sense.
It's perfectly right!
"My head aches right now, it is definitely a cold" should work too
It's really hard to pinpoint the exact phrasing for this one. One minute, the correct answers are super literal, the next they are not.
I don't think "now" is essential in the English translation. "I have a headache" already means is happening now