How is she when she is waking from her first nap? She could be UT at nap time, which is why you are getting the short naps. At 4 months most babies can do 1hr45 to 2 hours. (Esp after a decent night)
After a short nap that second A time looks too long, If you get a short nap you will need to shorten the next A to avoid OT which will also cause short naps and crying at nap time.
Try extending that first A a bit to see if you get a better nap (this can take a few days) and if you get a short nap keep an eye on your LOs cues and put her down earlier than you usually would. Her As later in the day are quite long considering she is short napping.
Also for all her afternoon naps, the minute I put her down, she screams and cries for at least 15 minutes, sometimes longer before passing out.
Okay so with this...when you say cries and passes out, are you in the room with her shh/patting or helping her to sleep, some babies prefer pressure, or only patting or shhing? If you are leaving her in the room to cry alone this will not help, CIO is not supported by BW and also breaks the bond of trust between mother and baby.
I really think this is likely to just be a routine or developmental issue and things will come right. In the meantime you can also try W2S on her short naps to see if this will help her to extend them. Do you know what W2S is and how to use it? - I will hunt out a link