A cold with a D&C just two weeks behind you is common, since any recent procedure can leave you a little run down. Azithromycin and Montek LC are both routinely used for this kind of infection and are generally fine to take together, and taking them isn't expected to affect your recovery from the D&C.
Next Steps
Rest, stay hydrated and keep an eye on your bleeding pattern since it should be settling by now. Please check with your gynaecologist before starting them if they weren't the one who prescribed this combination.