Did your employer invest additional money for your upgrade to “lead” captain? If yes, well a pay freeze may not unreasonable for a few trips so you can prove yourself. However, be prepared for your current position to be temporary as they may be searching a “lead” captain that meets their total requirements, while you meet their requirements as either a co-captain, or normal line captain without management responsibilities.
By the way how many of aircraft in your company. If more than one, are you qualified on all aircraft?
Anyway, with your promotion to “lead” captain;
Are you managing other employees such as F/Os, cabin crew, ground and or Maintenance personnel, and ground handlers?
Do you have to arrange your flight plans, overfly, and landing permits, catering etc.?
If you are ready to take a walk, do you have any alternative jobs lined up? And if so, are you prepared to tell your employers to go $hit in their hats if they don’t give you a raise commensurate with your increased responsibilities? If not then this whole discussion is moot.