This should do:
import random
num = random.randint(7, 14)
print num
message = ""
prevnum = -1
for n in range(num):
newnum = random.randint(100, 103)
while newnum == prevnum:
newnum = random.randint(100, 103)
prevnum = newnum
message += chr(newnum)
You have made numerous mistakes in your code, you should review them.
solved While Loop and if statement