Recovering from pneumonia

I am 71 year old , generally healthy female. was diagnosed with pneumonia at the ER 2 1/2 weeks ago. It was seen on a CT scan. They put me on IV antibiotics for several days and by mouth for days after that. Since I’ve been completely exhausted and fatigued. It was the 2nd lung infection I’ve had since December. I had another CT scan two days ago as a follow up. It appears still healing from pneumonia, but they saw a 2 cm mass and said I should follow up with a PET scan. I have a message into my pcp regarding this. I have been a patient of Mayo Clinic before for surgery and other issues. I had to cancel follow up appointments ( other issues) this week (live somewhere else),because I don’t think I’m strong enough to travel. If I were to come back for those appointment, also get my lung followed up. How long should I wait? I understand I need to wait till the infection is resolved before another CT scan or PET scan to get accurate diagnosis w/ mass?