You are right to question some of your approach to your son, though his disposition is not your fault. He doesn't cry for no reason. Now, you might be of the opinion that the reasons he cries are not substantive, but there are clearly reasons - you have illustrated them well in your note. Your son does appear to carry a significant load of negative self-perceptions, and these color his experiences, contribute to easy frustration, and interfere with his confidence. Therapy can be useful in addressing some of these things. You can help as parents by maintaining your equanimity. Anger is not helpful, and is certainly not necessary. Sometimes as parents we think that our emotional reactions to our children are automatic, that we cannot influence them. But when we become angry we are choosing to do so. For you or his mother to be angry with your son about his reactions is not reasonable - his reactions don't deserve anger. In fact, by displaying anger you will be conveying rejection of him, and that will certainly exacerbate the problem. But enough of that - I think you get my point. He needs to get some success experiences under his belt - that is how children's self-perceptions become positive. The experiences themselves can be anything, whatever your son prefers to do. When he comments negatively, you don't have to respond. Rather, as in the example of fishing, just proceed to fish. In other words, don't let the pessimistic outlook get in the way. One thing to be vigilant about is whether the easy frustration and crying are symptomatic of a depressive disorder, and consideration of this is another reason to pursue some professional evaluation. If there is a family history of depression, your son will be more vulnerable to such a condition than would a child without such a family history.
Please have your son evaluated by a medical professional. I had a very similar situation with my son ( he's now 21) but I didn't do anything fast enough and it did create worse problems later. Believe me, he is crying for a reason but it is not your fault!
I know I post on the same subject, but only where I think it's appropriate. That's probably the best description of how easily emotional my son (now 8) was; how he displayed low self-esteem, etc. Yes, he needed successful experiences and to learn to think about himself more positively. HOWEVER, my son had severe problems accomplishing this (even with help and structure) until we addressed the real problem of a sleep disorder. Your mention of ear infections and allergies leads me to suggest you also request an evaluation for childhood sleep disorders (like obstructive breathing) that cause poor sleep quality and sleep deprivation. On the one hand, he needs the systmatic structure of parenting and support, but identifying the sleep deprivation for my son made all the difference and it's so often overlooked. Not only was he highly emotional, his anxieties were heightened so that he just couldn't cope throughout the day. I should say that my son's problem required medication (clonazepam, 0.5 mg) which regulates his sleep but is also an anti-anxiety - which also helps, i think. The difference was night and day almost. Within 2 weeks, his ability to function was unbelievably different and he started gaining more control of his responses. His interations with his peers and others improved greatly, i didn't expect the impact that treating the sleep problem made. We did a trial wean last summer...within 3 weeks he was back to negative self-image, whining, meltdowns, all of it.
hope that helps.