Concern on health before going in to flower

Hi everyone, I've a plant that is starting to bud and I'm a bit concerned about the plants health at this time. I've ben growing her in a home made grow cupboard for about 3 months old and she stands just under 3foot tall from the ground. I have it in a pot measuring 9x9 inches and 5 inch deep soil. I water regularly and use liquid plant food (Fish-Mix) once a week or so diluted as per instructions. She was quite healthy until a week or 2 ago when the lower leaves started to yellow and go harder but the tops were all good. Now the top sections also seem to be wilting and curling although no yellowing or stiffening. Here are photos of the plant and the soil I have it in. I was able to easily lift the soil block from the container for the shot.

From reading other posts I think it may be that it has become rootbound and I should add a little more soil which I can do from underneath or on top. I would think adding underneath is best but welcome comments or thoughts. I would also welcome any thoughts in relation to continuing to keep up the fish-mix or if I should stop during flowering.

Here are the pics and all thoughts and comments are welcome.

Look like it over feeding and make sure you dont have bugs or worm or fungus . on one pic i see many black dots .. that look fungus to me or a bugs .. i would flush them and spray with purespray .. good luck