Mix Dynomyco in water?

Nah I dont think you need it - it would take several days for the fungus to bloom and synergise with the root system, the fungus aids water and nutrient absorbtion across the root system. The plant is fading already which means either it is going into the death cycle from here and sucking the nutrients out of its leaves or it is getting hungrier as bud production ramps up, I would say try giving it a nice little feed and see if the colour picks up - if it doesnt you are in the end game and there's zero need for adding the fungus, if the colour does pick up your rhizosphere is working just fine and needs nothing extra - save the resources for your next grow and put what you have learned into action! ;)