Could a swollen ankle be a result of stress fractures that happened 7 years ago?

Re-injury. Yes, a swollen ankle could be from an old injury. You may have developed arthritis in the ankle or you may have re-stress fractured it. You should definitely see your podiatrist for x-rays and evaluation.
NO... After 7 years the stress fracture is long since healed. The swelling is from something else. See a doctor for an exam.
No. The swelling you have noe is unrelated to injury that occurred 7 years ago. Elevate and check with pcp and possible referral.