Hi ! I have a mybb forum. Until today I had no keywords. I was on page 2 at google search "webmaster forum". Today i added some keywords, like "webmaster,webmaster forum, seo," etc, but when I search webmaster forum now, my website is not even into the first 10 pages. my site is: www.rowebmaster.com
Your site is pretty new and I dont believe it is because you have added keywords that you lost your serp. You will need to do some major seo to get good serp for your desired keywords.