Tomas achieved the near-impossible against Fulham on Boxing Day by getting a yellow, followed straight away by a red card for talking in an unseemly manner to Dermot Gallagher in the 1-1 draw with Fulham, and he admits the expulsion has taught him a lesson.
"I spoke with Glenn and Paolo Di Canio on Tuesday and the red cards and, hopefully, the yellow cards, will finish," he says.
"It is my football to be aggressive - but I will not be talking to the referees.
"I must be 'easier', not get involved, and put those things in the past.
"It has been frustrating to miss four games; you are training every day with no match at the end of it."
Tomas has retained his optimism for the fight ahead, however, and he adds: "Maybe this game will change the season, Paolo Di Canio is back, and for me three points are very important, as is Sunday.
"With two games at home six points are possible; we have good players here but it is difficult for everyone, the internationals in the side, me, the others - but I think we can stay up if we win, or at least get four points, in these next two games.
"I feel strong mentally and have to show a big personality; it is a big test for all the players."
Tomas was given a poor reception by some fans when he came on as a substitute against Nottingham Forest a couple of games after he had been sent off for dissent against Fulham - and he is determined to win them over.
"For me it was no good to hear the boos but maybe I can change that and get them on my side - that is very important for me."
He is asking for a little leeway as he is unused to a battle against relegation.
"In my career, this season is the first time I have been at the bottom."
Tomas says the focus should not just be on the defence even though so many goals are being leaked, and adds:
"It is not just the defenders; everyone is responsible, 11 players on the pitch - it is a team problem.
"We need a clean sheet but 3-1 or 3-2 is the same - three points is what it is all about."
And he denies a report in one Sunday newspaper that he has already thought about what might happen if the unthinkable happens and West Ham go down.
"With 14 games to go it is not possible to think about next season or leaving; I want to stay at West Ham in the Premiership," he insists.
With last season's partnership of him and Christian Dailly, for the moment at least, dismantled, he concludes: "Me and Christian can play well together but everyone can play well, and everyone can have a bad day."
But for Tomas, there is a real determination to make those 'bad days' a thing of the past.