Complex set of Equations using ode15s results in integration tolerances not being met.

I am trying to run a program which solves a coupled PDE system (approximated as ODEs) using the ode15s solver.

Upon running my code, I get the following warning message:

"Warning: Failure at t=0.000000e+00. Unable to meet integration tolerances without reducing the step size below the smallest value

allowed (7.905050e-323) at time t. "

The error occurs in line 165 of 'Version1_AM' and line 668 of 'ode15s'.

Currently, all parameters are set to 1 prior to the parameter search being carried out within the literature... However, for a simpler model (with only 2 equations) no errors/warnings were encountered under same parameter conditions, so I don't think this is the issue, and more to do with the code itself either in the main loop or at the LHS/RHS BC.

I also have noted that when outputing my EC data from the function, it only has 6 points, when in reality I want it to have 10,000 (length of my tspan vector). This is not problematic in my EC_regrowth function which, although not directly relevant to the problem, I have attached for completeness. I was therefore curious that if I output the data from this EC_regrowth function, can I input the EC data into my equations such that it knows what time-point to be on? I hope that is clear...

Any tips on how to solve this problem would be great, thank you.

(Codes are presented as an attachment).