I have asthma, allergies and pnd. I believe Benadryl (diphenhydramine) will curb my pnd, yet may harm asthma. Should I use it here and there at regular strength? Thank

Maybe maybe not. Often asthmatics do use antihistamines in cinjunctinwith their routine asthma meds. Discuss using a non-sedating antihistamine like Claritin with your phsyician. Have you tried nasal saline which does not affect your asthma and may reduce your pnd.
Benadryl (diphenhydramine) is OK. It used to be thought that antihistamines with drying side effects (anticholinergic) may make asthma worse. Not true. In fact it can help asthma. There are now asthma medications available that their only effect is anticholinergic like ipratropium in Combivent and atrovent inhalers and nebulizer solutions. As long as you are using other medications to control your asthma, using Benadryl (diphenhydramine) is fine.