From the history and symptoms you describe, there are two likely scenarios:
a) traumatic periodontitis (bruising of ligament supporting tooth)
b) cracked cusp syndrome (a 'hairline' crack in the tooth)
Both diagnoses would fit your symptoms, and both are unlikely to show up on a radiograph. I would assume that your dentist checked for a cracked cusp.
If diagnosis a), then time and Ibuprofen will allow to settle and no treatment usually needed
If diagnosis b), then dental intervention is usually needed and treatment can include root canal therapy and provision of a crown, although this is not always needed.
I would support your dentists plan of action, ie monitoring the situation. If all settles, then fine. If symptoms persist then to return to your dentist for reassessment and treatment.
If your holiday is in 2 weeks, your should have some idea as to the outcome in a few days. Yes it's possible for the tooth to devitalise and form an abscess but the timescale for this is variable and may never happen at all.
I would simply go easy on it for a few days and return to your dentist next week if not settled.
Hope this helps.