My 10 month old gets a rash on his belly and in his diaper area when, that is also accompanied by a fever, when he eats fresh strawberries; however he is also teething, I've taken him to the pediatrician who has run labs. .. That say it is viral? Is it al

Teething. Teething typically doesn't result in a rash. The rash may be indicative of a strawberry allergy.
Berry allergy. Your child may be allergic to strawberries cease and desist the berries.
Immune rash. The immune system does odd things. Kids who are teething have slightly activated immune systems, and that can cause non-descript red bumpy rashes on the chest or diaper area. Viruses can do the same thing, and kids who are teething catch a lot of viruses. Strawberries and other foods can cause a contact irritation in the diaper area when some is mixed with the poop. But no, it's not always viral.
Allergy? What you described sounds/looks more like a reaction to strawberries. My suggestion is to avoid strawberries until you can test his response. When your child is healthy, no runny nose and has no other symptoms then give him a small amount of strawberries and monitor the response. You should be able to identify if it is an allergy or not then. It sounds like you suspect it may be an allergy anyway.
Teething. Teething can cause sore gums, but a fever only comes from an infection. The infection could be viral or bacterial. If the baby is run down at the time of teething he or she is more likely to get an infection.