Finished antibioitics a week ago now have dry tongue & it feels funny - could this be a side effect

It sounds as though you have oral thrush - a common yeast infection and side effect of broad spectrum antibiotics.
You will probably need to take an anti-fungal lozenge or mouth wash for a week or so. See your doctor or pharmacist for more advice.
https://www.drugs.com/cg/oral-candidiasis.html

Yes and it may be that since you were on 2 powerful antibiotics back to back, it killed off all the good bacteria that would have kept yeast from taking over. Try eating yogurt 2 to 3 times a day for a couple of weeks to see if that fixes the problem or call your doctor or dentist and report this. Both of these meds do continue to work for a few days after the last dose, There also is a mouth rinse called Biotene that is available at all drug stores and mass retail stores and it if for dry mouth and mouth irritations, it has NO alcohol, was developed for chemo patients without sodium lauryl sulfate, and contains natural enzymes that are supposed to be in the oral cavity.