What is wrong with my model? Can anyone help me to see what's wrong with it?

I am an undergraduate university student trying to model cell volume regulation in a certain cell type on Simulink. I am trying to get my cells steady before I make certain changes to it but whenever I run my model now I get 31 similar saying this:-

Unable to reduce the step size without violating minimum step size of 1.0658141036401503E-12 for 1 consecutive times at time -299.99178879442104.  Continuing simulation with the step size restricted to 1.0658141036401503E-12 and using an effective relative error tolerance of 0.0063371320531123128, which is greater than the specified relative error tolerance of 0.001. This usually may be caused by the high stiffness of the system. Please check the model 'CVRModel150324' or increase the Max consecutive min step size violation parameter in the solver configuration panel