ok a few things working against you here,
1 rule of thumb to follow, is you always want more plant than pot before you up pot/ transplant, usually u want to stay in the Dixie cup til your about 4 or so nodes in at least, and from there I would go to a 1gallon pot or slightly bigger, u need to develop the roots, u need to create a good healthy root ball before trying to go up a pot size, a few problems with jumping pot sizes before establishing a healthy rootball in the current pot are, u risk the roots not trying to reach for the edge of the pot but instead chasing the water straight to the bottom leaving you with a poor root structure, heading for root bound, and you run the risk of overwatering and running into the risk of not being able to control feeding and problems in a too big pot.
2. u want to usually increase lights gradually, meaning u need a plan. say your biggest light, being your 1000watt Light is your finishing light. a 1000watt light requires a 5x5 canopy about 3ft deep. and you want the lights about 2 to 3 feet away from this 5x5 canopy. usually u increase the light as the plant sizer increases, for eg. seedlings and starting clones u want a low wattage light...any around 24watts of flourescents, about 6-12incches away or 150watts of hids 2-4ft away. and this brings us to the next issue.
3. too much light! the most common mistakes new growers make is...too much light, too much water, too much nutes. you blasting this poor little guy with 1000watts of light. remember 1000wats supplies a canopy 5x5 and 3ft deep at a distance of around 3/4feet from the canopy. the best option would have been to increase your light slightly, a smaller veg light is needed for this size plant. one thing you can do is raise the light all the way up. but remember you will pay for this come flower time when you plant is bigger and calling for more light than it got in veg. if the recommended distance of your light is 3-4feet away from a 5x5 canopy, this doesn't mean keeping it this distance from much smaller plants, you are basically not allowing the plant to grow under the space of this light, with this big of light I would suggest getting that light at least 5feet away from this plant and assessing from there.
4. using the old finger in the soil to test the first inch or two o soil and if dry water, is false info! your plants will tell you exactly when they want water, a good way to judge when to water is to allow the plant to dry out until it shows slight signs of underwatering...(sounds damaging?...no where near as bad as over watering!) the plant will put out a smell first, followed by a wilt/drop of the lower leaves later running to the top. when the first signs of the wilt/droop come, take this time to feel the pot, pick it up notice the weight, notice how dry the soil is etc. now just before the point of the plant begging for water, is when you should be watering. plants don't do well being put on a humans schedule, they do their own thing, and will let u know. u need to allow the medium to completely dry out before watering, this will prevent all these signs you are seeing.
also as some advice you should let your sick plant recover, wait til the speed bumping, drooping, weird/slowed growth all stop, then proceed in topping and shaping and defoliating...what ever techniques you want to apply, doing so now only furthers your problems.
I hope this answers most of your problems. I always urge people to research, study plant signs and problems...the plant will always show u what it needs when it needs it, its about playing the game of identifying what the plants telling you it needs then giving what it needs, and it will always show/tell you first. including watering.
