What are my options?

I was hired in the capacity of a graphic designer in November. They were very happy with my performance for November. I was functioning in the role of content creator and social media management, branding and creating labels, website design, etc,. I was basically on every team in their start up. Jan 1st week they started complaining that they dont feel Im doing justice to the work, etc,. I told them they can relieve me - I will fulfill my duties as usual and leave the company. They disagreed. Instead they brought up a proposal of reducing my salary from 70k to 35k and I should continue to work since they're having financial tough times. They have a history of not paying employees that disagree with them and it was the 10th of Jan al ready, I was expecting my salary so I said ok.. They realised that I was saying ok but planned to quit and came up with another plan that my Dec and Jan salary will only be credited in April when the company gets funds :D I disagreed and said I will quit with notice if my salary is not changed or I will quit without serving notice if they cannot afford me. They told me Im fired and that I should leave with all my files - they dont need anything I was trying to leave but they brought me with another set of discussion and came up with another proposal, etc,. They finally agreed to pay me Dec salary only after they confirm my files. I agreed. My issue is they are not agreeing to pay me for Jan because apparently I did not do any work. Its 23k loss for me. I was incharge of coordinating their team for a design project that was pushed back because their web developer was not available. Is this fair. More details- I have completed 70 designs in the 2 months - Grew their social media by 20% - Assisted in re designing 60 product images for their product images which enabled their store to go live on amazon. - created and wrote 2 posts for their blog - Coordinate giveaway campaigns and influencers. - Created social media kits and posts for their sister brands - Carried my own laptop to work everyday which is why I still have the files I'm pretty sure this is more than enough for 2 months Do I have a case? What do I do?