I have seen similar questions to this problem with no answers, so after getting help from a colleague I wanted to post the solution
The other thing that was changed from my original question, is that it became piecewise to better satisfy the reference of the levy flight equation I posted myself. The starting vals I chose were arbitrary.
load('Speeds.mat')
[N,X] = hist(Speed,20);
Y = N/(sum(N))/diff(X(1:2));
%Get best parameters
modelFun = @(p,x) (x>p(2)).*(exp(-p(1)./(2.*(x-p(2)))).*(p(1)./(x-p(2))).^(3/2))./(sqrt(2.*pi).*p(1));
startingVals = [1,1];
coefEsts = nlinfit(X,Y,modelFun, startingVals);
%Visualize fit
bar(X,Y);
hold on;
model_eval = modelFun(coefEsts,X);
plot(X,model_eval,'r','LineWidth',2);
I wasn't aware of how to fit histograms in the first place, so hope this helps someone new to this!