I recommend having a soil test done. Your local Extension Service can help you with that. If you put an acid fertilizer on soil that is already too acidic, you will just make things worse. It's also not a good idea to fertilize any plant that is not doing well, unless you're certain lack of nutrients in the soil is the problem.
Soil with the wrong pH, i.e. too acidic or too alkaline, will prevent the plant from absorbing nutrients, even if there are plenty present in the soil. Adding fertilizer will just burn the roots and compound the problem.
Get the soil tested. If you do it through the Extension Service, they will also have suggestions for amendments to correct whatever the problem might be.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams