The size of testes keeps on varying with the temperature. It is not significant, unless there is pain, tenderness, etc over testes. About the penis going loose, it is normal after ejaculation. After ejaculation or orgasm the penis losses erections nad goes flaccid that is normal. If you are facing problems with early ejaculation, erections problem, etc Kindly consult directly with a sexologist.
Next Steps
For more information regarding this, you can also post a direct query here on practo or visit a nearby Sexologist.