Parameter Error in Fitted Data

I have a set of experimental data (3 columns of x data(concentrations) and 3 columns of y data(time)). In addition, I have 3 differential equations that describe the x values. I was able to fit 11 parameters that show up in the differential equations using fminsearchbnd which minimized the square of the difference between the experimental and fit values. This yielded a good fit. Also, I was able to obtain the individual parameter values which I will call k(1), k(2), ...k(11). Is there a simple call or example that can determine the error in each parameter such that I can report my parameter values with standard error as k(1)+/-#, k(2)+/-#, etc for all my parameters? Thanks in advance. Danny