It is not possible for the aphids feeding on the plum to transmit Strawberry Crinkle Virus (Cytorhabdovirus spp.) to your strawberries. Green Peach Aphid (Myzus persicae) is the only common aphid that feeds on both strawberry (Fragaria spp.) and plum (Prunus spp.) Strawberry Crinkle Virus is transmitted by Strawberry Aphids in the genus Chaetosiphon. Strawberry aphids only feed on strawberries and close relatives in the genus Fragaria.

The symptoms that you are seeing could certainly be caused by any number of things. Without photographs and/or descriptions of the symptoms, I cannot offer you a diagnosis. Virus symptoms in strawberry are usually not caused by infection with a single virus. Rather, symptomatic plants are infected with a complex of viruses. The best way to manage virus infections in strawberry plantings is to renew (i.e. remove all plants and replant with certified virus-free stock) every two or three years. There are no virus resistant strawberry varieties that I am aware of, but you could certainly ask your favorite nursery if they have virus resistant varieties available. 

If you'd like to have your plants tested for viruses or fungal diseases you can send a sample to the MSU Plant and Pest Diagnostics Laboratory. Their website has instructions and contact info for the lab: https://www.canr.msu.edu/pestid/