My 26 months old daughter has swelling on sides of both cheeks towards ears. she also seems to have pain. could it be due to teething?

Her doctor can check: A 2.5 year-old would already have had her MMR vaccine to protect against measles, mumps, and rubella. However, vaccines are not 100% protective, so catching mumps is still possible. Also, there are other viruses and bacteria than can cause similar symptoms, so such a child should be seen by her doctor. Her second molars could be coming out, but her doctor should still have a look.

Yes, but: Could also be mumps. Was she vaccinated? Please see your Pediatrician. Also see your a Dentist. 1st Dental examination should be at Age 1, preferably with a Pediatric Dental Specialist.