I don't think flushing will help anything, especially if the soil is holding onto water. Transplanting may be an option. Just keep in mind that transplanting will most likely stunt the plant, which is already stunted. Im pretty sure it's not an issue with nutrients.. I'm starting to lean towards the start of root rot. If the roots have been sitting in damp soil for 5 or more days with no change in appearance, I would start looking into the root zone, to see what the roots look like. Brown is bad, white is good. Im actually dealing with the same kind of issue on one of my photo period plants.. The soil isn't really draining at all. It holds moisture hostage and the plant is stunted because of it. 6 weeks veg, only 7inches tall. It takes almost 7 days for the soil to dry out. If you decide to transplant, try adding more perlite to the soil before you place the plant into the pot. That will help it dry out faster/better.