Is leaving a stitch in an incision for 7 months after the procedure, considered malpractice?

Medical malpractice is negligence.  Negligence is the failure to exercise due care (that degree of care that a reasonable medical practitioner in the community would have exercised under the same or similar circumstances to prevent foreseeable harm).

Prior to filing a lawsuit for negligence against the first doctor, it may be possible to settle the case with that doctor's malpractice insurance carrier.  Obtain your medical bills, medical reports and documentation of any wage loss.  Your claim filed with the first doctor's malpractice insurance carrier should include these items.  The medical report from the second doctor may provide evidence of malpractice. 

Compensation for the medical bills is straight reimbursement.  The medical reports will document the nature and extent of your injury and will be used to determine compensation for pain and suffering, which is an amount in addition to the medical bills.  Compensation for wage loss is straight reimbursement.  If the case is settled with the first doctor's malpractice insurance carrier, NO lawsuit is filed.  If you are dissatisfied with settlement offers from the first doctor's malpractice insurance carrier, reject the settlement offers and file your lawsuit for negligence against the first doctor.  If the case is NOT settled with the first doctor's malpractice insurance carrier, you will need to file your lawsuit for negligence against the first doctor prior to the expiration of the applicable statute of limitations or you will lose your rights forever in the matter.