Lump/recurring hive on lower abdomen

Age: 18

Sex: M

Height: 5'11'

Weight: 145

Race: White

Duration of complaint: 6/7 months

Location (Geographic): Northeast US

Location (on body): Lower abdomen, on right side adjacent to navel

No existing relevant medical issues.

No current medications.

To give some more detail, most of the time this condition can be felt (but not seen) as a firmer, slightly raised area underneath my skin. On occasion, a single hive (that isn't very itchy) will develop over the exact location of the firmer area (usually in the evening), then go away after a few hours. For about 4 years, I was taking somatropin injections, of which the problem area was one of three rotating injection sites. Therefore, I was thinking that it would possibly be a lipohypertrophy but that wouldn't explain the hive.

Pictures (first one was taken March 2017 in the morning, second was taken July 2017 in the evening): http://imgur.com/a/I4Yy0