Brief Answer:
most likely muscular
Detailed Answer:
HI, thanks for using healthcare magic
There are different possible causes of pain that can occur in the bony and soft tissues (muscles, ligaments, surrounding fatty tissue).
Infection of any of these areas would cause fever, redness, warmth, significant impaired mobility , loss of appetite,
fatigue and
malaise.
In the absence of these, infection is not likely.
Such there was no history of severe or sudden trauma then
fracture or any other severe injury is unlikely. Ligamentous injuries are uncommon in this area.
The pain is likely muscular. Though it did not start during the exercise or immediately after, this is common.
Pain due to
soft tissue injury can increase in a plateau fashion reaching its weak 24 to 48 hours after the initial insult or injury.
Unusual or excess use of soft tissue can produce this response. Normally it is self limited once the injury is not aggravated. It should last no more than 7 to 12 days and during that time the intensity should be decreasing.
You may want to consider the use of an anti inflammatory pain killer to reduce the inflammation that would be contributing to your discomfort. This includes medications such as
naproxen,
ibuprofen,
aspirin.
These should be used on a full stomach.
I hope this helps,feel free to ask any other questions