Welcome to healthcaremagic.
Asthenospermia usually not associated with painful urination or painful erection .
this symptoms may be presenting feature of u t i .presence of infection may result in poor motility of sperm. control of infection will help relieving yoursymptoms and improving the motiltyif infection be the reason of asthenozoospermia
please consult surgeon /urologist
and get a check up to find out any surgical
cause llke varicocoel,etc. that may have to be treated surgically .get a check up and discuss with surgeon
hope your problem is over .