We had a horrible experience with difficult child 3 on Strattera. It also made him very anxious, very aggressive and easily upset to rage point. We took him off it after only three days, but it was three days of utter ghastly mess.
I agree, a 5 year old is unlikely to be trying to manipulate you.
Also important to realise about 5 year olds - they don't understand the finality of death. Of course he is just as much a risk (perhaps more so) because of this lack of understanding, but what he is trying to say, is that he feels really, really bad and wants someone to make it stop, or HE will do something drastic to make it stop.
I'd be talking to someone in an emergency capacity (either the prescribing doctor, or the ER) and giving serious consideration to Strattera NOT helping and perhaps taking him off it (you need to ease off it if you can).
I know they don't like to give stimulants to kids with anxiety issues. This is why they tried difficult child 3 with Strattera. But for him, the stimulant makes it easier for him to concentrate and THINK, which in its own turn helps his anxiety level ease. So although anxiety ids a concern for us, the stimulant medications actually help.
It really helps if you can fully understand exactly what the child's problem is. You may be able to ask the neuropsychologist to call you if there's an earlier cancellation; but ubtil then, I would be blockading the prescribing doctor's rooms until he can be consulted with.
In our case, we rang the ER (our problems came to a head late at night). Because difficult child 3 had only been on Strattera for 3 days we made an executive decision to take him off it. But I rang his specialist as soon as his offices opened on Monday and reported in. The specialist called me as soon as he could (within an hour) and we talked. He endorsed taking difficult child 3 off the Strattera, reminded me he hadn't been happy to prescribe it but it was on the recommendation of a more senior specialist.
It may not be as simple as this for you, but if you go back over your own records of your son's history, you might see a pattern.
Keep your own good records. The sort of problems you've reported here, need to be in a diary of your own on your son. You may never need it; but on the other hand, you may. Or in ten years' time a specialist may ask a question you can't immediately answer. Having your own detailed diary from the past is a very useful tool.
Hang in there. He sounds very upset but at least he was smart enough to tell people. Hugs to him, and to you.
Marg