Yes, but you need to take the Mylanta 2 hrs after taking the nexium or it will block the absorption of the medication.
so?
yes
Yes
You can take antibiotics with Nexium but antibiotics given in combination of Nexium can cause life threatening complications in some of the patients, an uncommon adverse effect. If you are unsure if your particular antibiotic will affect you adversely ask your pharmacist.
yes
yes
Yes, you should continue to take methotrexate unless your doctor advises you to stop.
Yes, sometimes vets do give methotrexate, but it is in combination with other medications, and usually in extreme cases. If you have human methotrexate, do not attempt to dose it to your dog. This should only be done under vet care. Methotrexate is fatal if not given correctly.
Yes, you can. You will actually be more likely to get infections, and get them worse, when on methotrexate. At some point, you will likely need antibiotics.
You can. There is no interaction between these drugs.
Ask your doctor.