itemhilfe = random(5); // itemhilfe becomes 1, 2, 3, 4 or 5
Wrong!! that gives you 0.000 till 4.999 in steps from 0.001. Read the manual !!!!!!!!
Use:
itemhilfe = integer(random(5) + 1);

if (big_use = 1)
Wrong!!
should be:
if (big_use == 1)


After that two things that is false at your code i stop searching for more. Better you make the Workshop