hello and welcome to HCM,
A one sided discharge which comes and goes and increases when you strain is not a good sign.
It may be a condition called CSF rhinorrhoea
and is very likely because of the symptoms you have described especially the discharge and the clear nature of the discharge which is reminiscent of the CSF.
In this particular condition, because of a small defect in the roof of your nose, the brain fluid leaks out through the nose. A potentially dangerous condition as it may lead to infection of the brain.
You need to IMMEDIATELY consult your ENT and impress upon him to perform an Endoscopy
examination and also a CT (preferably a contrast CT to get the site of leak)
Furthermore do not strain or rinse your nose unless the above diagnosis is either confirmed or excluded
If possible collect the fluid which is coming out in a clean (preferable a lab sterilised) bottle so that can be sent to a test called the CSF analysis
take care and get well soon
Dr Sriram Nathan