Scar tissue is always a possibility after any surgery. However a residual dorsal hump is more likely due to leftover cartilage and bone than to scar tissue. You should look around and find someone else are comfortable with and after making sure you have adequate time to heal from the first surgery move forward with a revision.
Scar tissue formation is possible but you need to verify that the residual fullness is scar tissue. Having done revision surgery for many years I've found that post-op scar tissue is rarely a problem except in patients with very thick skin.
I think an exam in person is essential to determine where the bump is and what it may be from. If it is residual bone, it can often be shaved down.
The most likely occurrence from your first rhinoplasty is an under-correction of the original problem, not scar tissue. Injection of steroids is rarely needed following a rhinoplasty and if used improperly could lead to thinning of skin. I would advise you to be evaluated by a board certified plastic surgeon with a lot of experience with rhinoplasty and revision rhinoplasty. Good luck!