The Dragons currently lie in eighth position but turned-around a six match losing-streak against the Scarlets to seal a 26-9 victory and a place in the cup semi-finals.
Now Thomas, who only recently returned from long-term injury, reckons the Dragons can kick-on in the league.
The Men of Gwent face Edinburgh next, the beginning of a busy period in the Magners League.
"We've got some momentum going into the Magners League now," said Thomas. "Edinburgh will still be quality teams but we hope to get some wins in the next weeks and move up the table.
"It's massive to be in a semi-final, anything can happen and we can take a lot of confidence from this.
"We've struggled at the start of the season with injuries, but it's great to have Joe Bearman and Matthew Watkins back as well."
Thomas was the star of the show on his Rodney Parade homecoming against the Scarlets and capped a fine performance with two second-half tries.
But it has been a long road back to action for the fullback who fractured his leg in five places, dislocated and ruptured the ligaments in his ankle against Cardiff Blues in the Magners League last April.
"It's a massive relief, nine months is a long time and just to get back out on the pitch is fantastic," added Thomas. "I need some more matches under my belt now and I started to cramp up a bit after 70 minutes.
"But scoring those two tries was massive for my confidence and I hope to kick on from here, though the tries were down to the team, not me."
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