I had similar download issues then I starting having upload issues. But not on 3G, Im having issues with the Wifi.
I was uploading/MMS pictures all night on 4G, no issues. Went home and got on my wifi network and pictures would not send via SMS/MMS. 10 minutes and still had a "sending" next to the picture. Clicked off the Wifi, sent in less then a minute. WTF?
Reset my wifi, had friends send out stuff over Wifi with no issues. Restarted the phone. Still not sending. Finally i sent a pic and just let it sit there, 15 minutes later it worked.
This better not be the start of more issues, Ill loose my mind!!