Aches and pains in joints or muscles, most likely from the Lantus. Not 100% sure of course, but it is a known side effect and the pains disappeared after switching to Tresiba.
One time one of those dreaded 'Lantus lows', where some Lantus hits a small blood vessel making it act like a very quick acting insulin. Happens within half an hour after injecting, very scary. After googling and finding out the cause of this bizarre low I demanded to be switched to another insulin right away.
Happy with Tresiba.