To find the next minimum and maximum after the global maximum, use the "findpeaks" function, but limit the data to after the global maximum occurred. See the attached picture with the output of this code.
% Sample Data:
x = 0:0.1:20;
y = sin(x).*exp(-abs(x-10)/10);
plot(x,y);
hold on;
% Find global maximum and its index
[globalMaxY,globalMaxIndex] = max(y);
globalMaxX = x(globalMaxIndex);
% Plot global maximum in red
plot(globalMaxX,globalMaxY,'Marker','o','MarkerSize',10,'MarkerEdgeColor','red');
% Create a subset of data limited to after the global maximum
xSubset = x(globalMaxIndex:end);
ySubset = y(globalMaxIndex:end);
% Find the minimum peaks after the global maximum
[negHeights,xMinLocations] = findpeaks(-ySubset,xSubset);
minPeakX = xMinLocations(1);
minPeakY = -negHeights(1);
% Plot the next minimum in blue
plot(minPeakX,minPeakY,'Marker','o','MarkerSize',10,'MarkerEdgeColor','blue');
% Find the maximum peaks after the global maximum
[heights,xMaxLocations] = findpeaks(ySubset,xSubset);
maxPeakX = xMaxLocations(1);
maxPeakY = heights(1);
% Plot the next maximum in green
plot(maxPeakX,maxPeakY,'Marker','o','MarkerSize',10,'MarkerEdgeColor','green');
% From here you can compute x and y distances between the given maxima and minimum.
