from my personal experience trimming the lower fan leaves allows much more light to reach the bottom-center of the plant causing more healthy growth. although i'm sure other people will disagree. you spend the most time with your plant, do what you think it needs.
i would start over, they look way to stressed to continue growing.
also i am new to this forum however, people attacking others because they asked for help is unnecessary and almost defeats the purpose of this section of the forum... just my two cents.
Got rid of my gnats with a package of the sticky fly traps that you hang up from Walmart. After the first week they were pretty full. Not the best solution but it worked for me and was a cheap/quick fix.